Numerous types of apparatus have been used in the past to sever desired lengths of material from a moving continuous length of material. Two types of prior art devices are flying shears and flying saws.
Flying shears utilize shear blade assemblies which have a width equal to the width of the material to be cut. The cutting operation is thereby accomplished by a single passing or shearing motion downward through the entire width of material. Examples of flying shears are found in U.S. Pat. Nos. 3,704,643 and 3,811,354.
Flying saws utilize cutting blades, generally circular rotary driven blades, which have a size smaller than the width of the material to be severed. Thus, in a flying saw, the saw blade must be moved transversely across the width of the material to be severed. Examples of flying saws are found in U.S. Pat. Nos. 1,924,162; 3,133,850; 3,190,162 and 3,620,887.
The flying saw disclosed in the U.S. Pat. No. 1,924,162 patent is adapted for cutting a sheet of fiberous composition, particularly a sheet of material from a forming machine, such as a Fourdinier machine. A main carriage is driven parallel to the direction of motion of the material by coupling the main carriage to an endless chain which in turn is connected to the main drive of the material to be cut. See FIG. 2 of the '162 patent. The main carriage includes a pair of tracks extending transversely of the direction of motion of the material. A saw supporting carriage is supported for transverse motion on the tracks. A motor driven saw is carried on the saw supporting carriage. The transverse motion of the saw is accomplished by the pulling action of two cables. One of the cables has one of its ends connected to one of the sides of the saw supporting carriage and its other end connected to a main support frame, and the other cable has one of its ends connected to the other side of the saw supporting carriage and its other end connected to the main support frame. As the main carriage is moved longitudinally, the saw support carriage is thereby moved transversely by the pulling action of the cable.
The '850 patent discloses a process for manufacturing plywood, including a saw device for cutting a continuous length of plywood into separate pieces. The saw device is clamped to moving plywood so that the saw device moves concurrently with the plywood. The clamping action is initiated by a limit switch. The limit switch also activates a motor which drives a circular saw transversely of the plywood. The saw device is moved in a direction opposite to the motion of the plywood by a pneumatic cylinder which is activated after the saw device is unclamped from the plywood. A subsequent cut by the circular saw is thereafter accomplished in an opposite transverse direction.
The '887 patent discloses a method and apparatus for manufacturing plywood including a cut off unit for cutting separate sections of plywood from a moving continuous length of plywood. The apparatus includes a carriage which is driven in the direction of motion of the plywood to be cut by spaced endless chains connected to the carriage by links. The endless chains are driven by a common drive motor. A subcarriage is carried on the main carriage and is movable transversely of the direction of motion of the carriage. An endless chain, driven by a separate electric motor, provides the power to move the subcarriage transversely. The carriage and subcarriage are mounted below the plywood to be cut and a circular blade projects upwardly through the plywood as it is cut. A photo cell actuates the cut off unit by initiating the clamping of the plywood and the drive of the drive motors for the main carriage and subcarriage. The sawdust produced during the cutting operation is drawn away by a vacuum dust. After the completion of one transverse cut, the endless chain coupled to the main carriage moves the carriage back to its initiation point. When the photo cell indicates the initiation of another cutting operation, the cycle begins again, with the subcarriage moving transversely in the opposite direction to the preceeding cut.
The 3,190,162 patent discloses a cut off machine wherein a saw is moved transversely through the material to be cut, such as rods passing from a casting machine. A clamp mechanism for holding the material being cut is activated by a rack and pinion, as illustrated in FIGS. 3 and 4.
Numerous problems have occurred with commercial prior art flying saws. For example, if the device uses an electric saw motor beneath the material being cut, the saw operates in an extremely dusty environment thereby causing excessive electrical problems. If the saw makes its cut in both directions, dust is thrown above the material, as well as below the material, thereby requiring an air pick up to collect the dust. When electrical signals are used to control the starting and stopping of saw travel, miscuts may occur. If saw travel is accomplished by air cylinders, the air cylinder operates at maximum capacity and speed at all times and is therefore prone to break down and high maintenance costs.